You can view your account invoices by logging into Member Zone, and clicking on the "View Invoices" link under the "Account & Billing Profile" section.

If you're logging into your Master Account, you will need to click on the domain name first before you can see the "Account & Billing Profile" section.

You can access cPanel by logging into Member Zone, and clicking on the "Access Site Admin Panel (cPanel)" link.  If you're logging into your Master Account, you will need to click on the domain name first before you can see this option.